@Black-Square One more.. @ark just alerted me to the fact that the AP button when disconnecting the autopilot, also disconnects PIT mode. The red yoke button does not do that. I suspect that the following is the culprit:
(A:AUTOPILOT THROTTLE MAX THRUST, bool) if{ (>K:AUTO_THROTTLE_TO_GA) }
If I remove that line, the problem goes away..
Remaining question: Why does the AP button turn off YD, but the red yoke button does not? Is that intentional?